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Researchers on board NASA’s Stratospheric Observatory for Infrared Astronomy, SOFIA, observed the collapse of portions of six interstellar clouds on their way to becoming new stars that will be much larger than our sun.
When a gas cloud collapses on itself, the cloud’s own gravity causes it to contract and the contraction produces heat friction. Heat from the contraction eventually causes the core to ignite hydrogen fusion reactions creating a star.
Astronomers are excited about this SOFIA research because there have been very few previous direct observations of collapse motion. These SOFIA observations have enabled scientists to confirm theoretical models about how interstellar clouds collapse to become stars and the pace at which they collapse. Actually observing this collapse, called “infall,” is extremely challenging because it happens relatively quickly in astronomical terms.
“Detecting infall in protostars is very difficult to observe, but is critical to confirm our overall understanding of star formation,” said Universities Space Research Association’s Erick Young, SOFIA Science Mission Operations director.
Using the observatory’s GREAT instrument, the German Receiver for Astronomy at Terahertz Frequencies, scientists searched for this developmental stage in nine embryonic stars, called protostars, by measuring the motions of the material within them. They found that six of the nine protostars were actively collapsing, adding substantially to the previous list of less than a dozen protostars directly determined to be in this infall stage.
For several weeks each year, the SOFIA team operates from Christchurch, New Zealand, to study objects best observed from southern latitudes, including the complete center of the Milky Way where many star-forming regions are located. Heading south during the Southern Hemisphere’s winter months, when the nights are long and infrared-blocking water vapor is especially low, also creates prime observing conditions.
“With the Southern Hemisphere deployments of SOFIA, the full inner Milky Way comes into reach for star formation studies. This is crucial for observations of the earliest phases of high-mass star formation, since this is a relatively rapid and rare event,” said Friedrich Wyrowski, astronomer at the Max-Planck Institute for Radio Astronomy in Bonn, Germany.
The results were from observations made in the Southern Hemisphere in 2015, and were published in Astronomy and Astrophysics earlier this year. SOFIA spent seven weeks during 2016 observing from Christchurch. The scientific teams involved in the Southern Hemisphere observations are analyzing the acquired data now.
SOFIA is a Boeing 747SP jetliner modified to carry a 100-inch diameter telescope. It is a joint project of NASA and the German Aerospace Center, DLR. NASA’s Ames Research Center in California’s Silicon Valley manages the SOFIA program, science and mission operations in cooperation with the Universities Space Research Association headquartered in Columbia, Maryland, and the German SOFIA Institute (DSI) at the University of Stuttgart. The aircraft is based at NASA’s Armstrong Flight Research Center's Hangar 703, in Palmdale, California.
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NASA Selects Next Generation Spectrometer for SOFIA Flying Observatory
A team from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, has been selected to develop a new, third-generation facility science instrument for the Stratospheric Observatory for Infrared Astronomy, SOFIA.
The principal investigator, Samuel Harvey Moseley will lead the team to develop the High Resolution Mid-InfrarEd Spectrometer (HIRMES). The team consists of co-investigators from Space Dynamics Lab, Precision Cryogenic Systems, Inc., University of Michigan, University of Maryland, Smithsonian Astrophysical Observatory, Johns Hopkins University, Space Telescope Science Institute, Cornell University and University of Rochester.
Moseley and his team will construct HIRMES over the next two and one-half years with flights on board SOFIA slated for spring 2019. At that time, this unique research asset will also be made available for use by the larger astronomical community.
“HIRMES will help researchers determine the location of the raw materials that are the building blocks of life and how their position within the interstellar medium helps planetary systems, like our own solar system, evolve,” said Hashima Hasan, SOFIA program scientist at NASA Headquarters in Washington, D.C. “HIRMES builds upon Moseley’s long history of superior instrument design. Included among his many achievements is the development of the microshutter arrays for the James Webb Space Telescope’s near-infrared spectrometer.”
The HIRMES spectrometer is optimized to detect neutral atomic oxygen, water, as well as normal and deuterated (or “heavy”) hydrogen molecules at infrared wavelengths between 28 and 112 microns (a micron is one-millionth of a meter). These wavelengths are key to determining how water vapor, ice, and oxygen combine at different times during planet formation, and will enable new observations of how these elements combine with dust to form the mass that may one day become a planet.
HIRMES will provide scientists with a unique opportunity to study this aspect of planetary formation, as SOFIA is currently the only NASA observatory capable of accessing these mid-infrared wavelengths. Infrared wavelengths between 28 and 112 microns will not reach ground-based telescopes because water vapor and carbon dioxide in the Earth’s atmosphere block this energy. SOFIA is able to access this part of the electromagnetic spectrum by flying between 39,000 feet and 45,000 feet, above more than 99 percent of this water vapor.
NASA anticipates soliciting proposals for the next (fourth generation) instrument on SOFIA in 2017.
SOFIA is a Boeing 747SP jetliner modified to carry a 2.5-meter, 100-inch, diameter telescope. It is a joint project of NASA and the German Aerospace Center. NASA’s Ames Research Center in California’s Silicon Valley manages the SOFIA program, science and mission operations in cooperation with the Universities Space Research Association headquartered in Columbia, Maryland, and the German SOFIA Institute at the University of Stuttgart. The aircraft is based at NASA’s Armstrong Flight Research Center's Building 703, in Palmdale, California.
Quelle: NASA